SINGLE CHIRALITY sc-SWCNT AND USES THEREOF IN PHOTO-ACTIVE DEVICES

Abstract

A composition for use in a photo-active device has: a charge transfer network of single walled carbon nanotubes (SWCNT) having at least 95 wt % of semiconducting single walled carbon nanotubes (sc-SWCNT) based on total weight of the SWCNT, the sc-SWCNT containing at least 30 wt % of one chiral type of sc-SWCNT based on total weight of the sc-SWCNT; and, a solution processible electron trapping material of a fullerene compound, the electron trapping material in contact with the charge transfer network of SWCNT. The composition is readily prepared from solution processible components and is highly sensitive in a narrow wavelength band. The composition is particularly useful in photoconductors and phototransistors that operate on the infrared region of the electromagnetic spectrum.

1 . A composition for use in a photo-active device, the composition comprising:
 a charge transfer network of single walled carbon nanotubes (SWCNT) comprising at least 95 wt % of semiconducting single walled carbon nanotubes (sc-SWCNT) based on total weight of the SWCNT, the sc-SWCNT comprising at least 30 wt % of one chiral type of sc-SWCNT based on total weight of the sc-SWCNT; and,   a solution processible electron trapping material comprising a fullerene compound, the electron trapping material in contact with the charge transfer network of SWCNT,   wherein the electron trapping material has a lowest unoccupied molecular orbital (LUMO) that is higher in energy than a highest occupied molecular orbital (HOMO) energy level of the one chiral type and is at least 0.1 eV lower than a lowest unoccupied molecular orbital (LUMO) energy level of the one chiral type.   
     
     
         2 . The composition of  claim 1 , wherein the LUMO of the electron trapping material is at least 0.2 eV lower than the LUMO energy level of the one chiral type, the LUMO of the electron trapping material is −4.0 eV or lower vs. vacuum energy or the LUMO of the electron trapping material is both at least 0.2 eV lower than the LUMO energy level of the one chiral type and −4.0 eV or lower vs. vacuum energy. 
     
     
         3 . (canceled) 
     
     
         4 . The composition of  claim 1 , wherein the sc-SWCNT comprises at least 50 wt % of the one chiral type. 
     
     
         5 . The composition of  claim 1 , wherein the sc-SWCNT comprises at least 75 wt % of the one chiral type. 
     
     
         6 . The composition of  claim 1 , wherein the sc-SWCNT comprises at least 90 wt % of the one chiral type. 
     
     
         7 . The composition of  claim 1 , wherein the SWCNTs are wrapped with a conjugated polymer, wherein the one chiral type is (6,5), (7,5) or (9,8) or wherein the SWCNTs are wrapped with a conjugated polymer and the one chiral type is (6,5), (7,5) or (9,8). 
     
     
         8 . (canceled) 
     
     
         9 . The composition of  claim 1 , wherein the one chiral type is (6,5), (7,5) or (9,8) and the electron trapping material comprises [6,6]-phenyl C 61  butyric acid methyl ester or [6,6]-phenyl C 71  butyric acid methyl ester. 
     
     
         10 . The composition of  claim 1 , wherein:
 the electron trapping material is homogeneously mixed with the SWCNT;   the electron trapping material and the SWCNT form a bilayer with a contact interface between a first layer comprising the electron trapping material and a second layer comprising the SWCNT; or,   the electron trapping material and the SWCNT form a bilayer with the electron trapping material interpenetrating into the SWCNT.   
     
     
         12 . (canceled) 
     
     
         13 . A photo-active device comprising:
 a substrate;   a source electrode disposed on the substrate;   a drain electrode disposed on the substrate; and,   the composition as defined  claim 1  disposed on the substrate and in contact with the source electrode and the drain electrode to permit electrical current to flow between the source and drain electrodes through the charge transfer network of SWCNT.   
     
     
         14 . The device of  claim 13 , wherein the device is a photoconductor and the substrate is an electrical insulator. 
     
     
         15 . The device of  claim 14 , wherein the substrate comprises glass. 
     
     
         16 . The device of  claim 15 , wherein the device is a phototransistor and the substrate comprises a gate. 
     
     
         17 . The device of  claim 16 , wherein the substrate further comprises a gate dielectric disposed between the gate and the charge transfer network of SWCNT. 
     
     
         18 . The device of  claim 17 , wherein the gate comprises doped silicon, the gate dielectric comprises silicon dioxide, or both the gate comprises doped silicon and the gate dielectric comprises silicon dioxide. 
     
     
         19 . The device of  claim 13 , wherein the substrate is a first substrate and the device further comprises a second substrate, wherein the composition is disposed between the first and second substrates, and the second substrate is an electrical insulator. 
     
     
         20 . The device of  claim 13 , wherein the source and drain electrodes comprise one or more electrically conductive metals. 
     
     
         21 . A process for producing a photo-active device, the process comprising: depositing a source electrode and a drain electrode on a substrate; and either
 (a) depositing on the substrate, between the source electrode and the drain electrode, a composition comprising a charge transfer network of single walled carbon nanotubes (SWCNT) such that the network is in contact with the source and drain electrodes to permit electrical current to flow between the source and drain electrodes through the charge transfer network, and depositing on the charge transfer network a solution processible electron trapping material comprising a fullerene compound, or   (b) depositing on the substrate, between the source electrode and the drain electrode, a composition comprising a charge transfer network of single walled carbon nanotubes (SWCNT) homogeneously mixed with a solution processible electron trapping material comprising a fullerene compound to permit electrical current to flow between the source and drain electrodes through the charge transfer network,   
       wherein in both (a) and (b) the charge transfer network of SWCNT comprises at least 95 wt % of semiconducting single walled carbon nanotubes (sc-SWCNT) based on total weight of the SWCNT, the sc-SWCNT comprising at least 30 wt % of one chiral type of sc-SWCNT based on total weight of the sc-SWCNT, 
       and wherein in both (a) and (b) the electron trapping material has a lowest unoccupied molecular orbital (LUMO) energy level that is higher in energy than a highest occupied molecular orbital (HOMO) energy level of the one chiral type and at least 0.1 eV lower than a lowest unoccupied molecular orbital (LUMO) energy level of the one chiral type. 
     
     
         22 . The process of  claim 21 , wherein, in part (a), the composition comprising the charge transfer network is deposited on the substrate before the electron trapping material is deposited on the composition comprising the charge transfer network. 
     
     
         23 . The process of  claim 21 , wherein:
 the depositing of the charge transfer network is accomplished by printing;   the depositing of the electron trapping material is accomplished by printing; or,   both the depositing of the charge transfer network and the electron trapping material are accomplished by printing.   
     
     
         24 . The process of  claim 21 , further comprising annealing the deposited charge transfer network on the substrate.